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Ban GMOs Now - Dr. Mae-Wan Ho and Dr. Eva Sirinathsinghji

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Living Rainbow H2O - Dr. Mae-Wan Ho

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The Rainbow and the Worm - the Physics of Organisms - Dr. Mae-Wan Ho

“Probably the Most Important Book for the Coming Scientific Revolution” - more

Transgenic DNA in Animal Feed

Critique of MAFF* Report CS0116

"Effect of feed processing conditions on DNA
fragmentation"

Angela Ryan and Dr. Mae-Wan Ho, Institute of Science in Society and Department of Biological Sciences, Open University,UK

Summary

A pilot study, commissioned by the UK Ministry of Agriculture, Fisheries
and Food (MAFF), was carried out in Leeds University to determine the
extent to which DNA in animal feed is degraded under various processing
conditions. It addressed concerns over the transfer of foreign genes
introduced into GM crops, especially antibiotic resistance marker genes,
to bacteria, which would render common infectious diseases untreatable.
The study involved analysis of non-GM material provided by the food
industry directly, or subsequent to small-scale processing in the
laboratory.

The main conclusions are that DNA is not degraded under most commercial
processing conditions, nor in the silage, and that further studies on GM
material should be undertaken.

Current animal feed is likely to contain substantial amounts of
undegraded DNA, and secondary horizontal transfer of intact antibiotic
resistance genes to bacteria and other organisms cannot be ruled out.

Other components of transgenic DNA may also have significant health
impacts on livestock and human beings up the food chain.

Recommendation

In view of the potential health impacts due to the secondary horizontal
transfer of transgenic DNA on livestock and human beings, all current
animal feed should be withdrawn immediately. Steps should be taken to
ensure that no GM material will be fed to animals directly or incorporated
into commercial animal feed.

*UK Ministry of Agriculture, Fisheries and Food, Report CS0116, London

Introduction

MAFF Report CS0116 describes work carried out in Leeds University to
determine the extent to which DNA is broken down in animal feed. Animal
feed is either fed raw and unprocessed, or after being processed under a
variety of conditions in commercial mills. The effect of several methods
of processing on the degradation of DNA in animal feed was investigated.
DNA degradation in raw foodstuffs from commercial and non-commercial
sources was also determined.

This work addressed concerns regarding the transfer of transgenes
introduced into GM crops, especially antibiotic resistance marker genes,
to bacteria. This would exacerbate the problem of antibiotic resistant
strains of bacteria associated with the recent resurgence of infectious
diseases such as tuberculosis. The rationale for the research is
presumably to identify conditions of treatment or processing of animal
feed which degrade DNA and prevent the transfer of intact, functional
antibiotic resistance genes.

The study has all the hallmarks of a pilot project, not intended to
provide definitive data on the extent to which DNA of GM crops, and more
particularly, transgenic DNA, would be degraded in different kinds of raw
or processed GM animal feed. No GM materials were used in the study, nor
was the presence of antibiotic resistance genes examined. Nevertheless,
the results give strong indications that DNA is not degraded under most
commercial processing conditions.

Materials and methods

Three major UK animal feed companies were involved with this study,
providing advice on processing specifications and a range of samples. It
was agreed early in the project that it would be better to process the
feed materials under closely monitored conditions at a semi-commercial
scale feed plant in the Roslin Institute, rather than in commercial mills.
However, there was considerable delay in commissioning the equipment at
the Roslin Institute, so the original plan had to be abandoned.

Oil seeds, before and after oil extraction by expulsion and
compression.

Wheat grains of the variety Riband, and smaller samples of 20 other
varieties.

Maize gluten and flaked maize.

Fresh wet sugar beet and dried sugar beet pulp.

Fresh ryegrass and rye silage.

In addition, fresh maize leaves and maize silage were obtained from the
University Farm, and fresh maize cobs and maize grains from the local
supermarket.

DNA was extracted by standard procedures. Two methods were used to
monitor the extent of DNA fragmentation. The first, agarose gel
electrophoresis, determines the size of the fragments, but does not give
any indication of their composition. It is also limited in sensitivity,
and will not detect undegraded DNA less than 1% of the total contained in
the sample. The DNA was judged to be degraded when the size of DNA
fragments is less than 100 base pairs. The second method uses the
polymerase chain reaction (PCR) to amplify DNA sequences and can detect
even trace amounts of undegraded DNA of particular gene sequences. The
particular gene sequence investigated was the small subunit of the Rubisco
enzyme from maize.

Results

The results on DNA degradation estimated with agarose gel
electrophoresis are summarised in Table 1

Table 1 The state of DNA in different samples and after different
treatments

Sample/Treatment

State of DNA

Wheat/grinding

intact

Wheat/milling

intact

Linseed leaves

intact

Linseed grains

intact

Wheat leaves

intact

Wheat grains

intact

Soya leaves

intact

Soya grains

intact

Maize leaves

intact

Maize grains

intact

Maize silage

intact

Rapeseed leaves

intact

Rapeseed grains

intact

Ryegrass

intact

Ryegrass silage

intact

Wheat/dry heat at 90 deg.C or below for 30 mins

intact

Wheat/dry heat at 93 deg. C for 4 mins.

intact

Wheat/low pressure steam, 60 deg. C for 30 mins

intact

Wheat/dry heat at 93 deg. C for 5 to 15 mins

partially degraded

Wheat/low pressure steam at 85 deg. C for 10 mins

partially degraded

Wheat/dry heat at 95 deg. C for 5 mins

degraded

Wheat/low pressure steam, 95-100 deg. C for 30 sec. or longer

degraded

Wheat/high pressure steam at 100-125 deg. C for 1 min. or longer

degraded

Oilseed rape meal after extraction

degraded

Oilseed rape cake

degraded

Maize gluten

degraded

Maize flaked

degraded

Dried sugar beet pulp

degraded

The PCR technique gave the expected amplification of the Rubsico subunit
gene sequence from maize leaves, grains and silage of up to about 600 base
pairs. It is not clear from the Report whether attempts have been made to
amplify the sequence from the other maize samples in which DNA was judged
to be degraded by agarose gel electrophoresis.

Conclusions

The results show that DNA remains intact in fresh plant leaves and grain
as well as in silage. Under even small-scale laboratory conditions,
temperatures of not less than 95 deg. C for at least 5 mins were required
to degrade DNA. Most commercially processed animal feeds are subjected to
temperatures not exceeding 85 deg. C. Where steam is used to condition
material for pelleting, temperatures reach at least the mid-80s for an
uncertain length of time, and the laboratory results show that DNA may
only be partially degraded under those conditions. The Report recommends
against using ensilaged GM material for animal feed, and concludes that
most commercially produced animal feed contains intact DNA fragments of a
size greater than 1200 base pairs  comparable to the beta-lactamase
antibiotic resistance marker gene used in many GM crops.

Critique

This work was a pilot study. It used non-GM material, and processings
were carried out on small laboratory scales. No attempt was made to follow
degradation of a specific antibiotic resistance marker gene.

No consideration was given to the transfer of other transgenic DNA, such
as the cauliflower mosaic viral (CaMV) promoter. The CaMV promoter is
about 350 base pairs in length and contains a recombination hotspot, which
makes it prone to break and join up with other pieces of DNA. It also has
several short sequences, less than 100 basepairs in length, with specific
functions for replication of the virus, which are interchangeable with
other viruses. Thus, the CaMV promoter may have an enhanced propensity to
transfer horizontally, with the potential to reactivate dormant viruses,
to regenerate new viruses and to cause cancers in mammalian cells.

The criterion of degraded DNA is the absence, on agarose gel
electrophoresis, of any fragment longer than 100 base pairs. This is not
sufficient to exclude short fragments which may have significant
biological activities from being transferred horizontally (see above).

The Report states there is no reason to believe that the conditions
necessary to fragment the DNA of GM plant material are different from
unmodified material. However, in the absence of experimental data, this is
mere conjecture. Transgenic DNA may have an enhanced resistance to
degradation, or not.

The small laboratory scale processings done in this study are unlikely
to reflect the effects of large-scale commercial processings. However, the
conditions used were more favourable to DNA degradation than those
that the materials are likely to encounter in the commercial setting.
Thus, the results give strong indications that most commercial processings
will leave DNA intact. We understand that the Chief Sciences Group of MAFF
have commissioned follow-up research on the effects of commercial scale
processing on the integrity of DNA in animal feed, and that the report
will be available by the end of March next year.

The scientists involved in the study are now working on "Assessment
of the risks of transferring antibiotic resistance determinants from
transgenic plants to micro-organisms" due to be completed in April
2001. In this new study, GM material will be fed to animals and transfer
of antibiotic resistance marker genes to micro-organisms in the animal gut
will be monitored by the PCR technique.

After the CS0116 Report was written, MAFF produced its own report, "GM
Materials in Animal Feed", which makes a reference to the work as a first
look study. But it fails to mention any of its important
conclusions. Nevertheless, from the data presented regarding the level of
GM material in British animal feed, it is clear that current British
animal feed comprises at least 20% GM material obtained from suppliers
abroad which do not segregate GM from non GM varieties (p.5). It is also
clear that up to 45% of raw material used in compound feed in Great
Britain in 1997/1998 contained cereals, peas, beans and vegetable
residues, all of which may have intact GMO-derived DNA.

The report gives no reference to other MAFF research conducted to assess
the safety of using GM material - MAFF project (FS 0204) showed that the
human mouth contains bacteria capable of taking up and expressing free DNA
and that similar transformable bacteria are also present in the
respiratory tract. Furthermore, in a letter from UK MAFF to the US FDA
dated Dec. 1998, it was pointed out that transgenic DNA may be transferred
not just by ingestion, but by contact with plant dust and air borne pollen
during farm work and food processing.